ARKit Audio-Video Recorder Asset Writer

prepareWriterAndInput.swift

public func prepareWriterAndInput(size:CGSize, videoURL:URL, completionHandler:@escaping(Error?)->()) {
        
        do {
            self.assetWriter = try AVAssetWriter(outputURL: videoURL, fileType: AVFileType.mp4)
            
            // Input is the mic audio of the AVAudioEngine            
            let audioOutputSettings = [
                AVFormatIDKey : kAudioFormatMPEG4AAC,
                AVNumberOfChannelsKey : 2,
                AVSampleRateKey : 44100.0,
                AVEncoderBitRateKey: 192000
                ] as [String : Any]
            
            self.audioInput = AVAssetWriterInput(mediaType: AVMediaType.audio, outputSettings: audioOutputSettings);
            self.audioInput!.expectsMediaDataInRealTime = true
            self.assetWriter?.add(self.audioInput!);
            
//            self.audioInput.
            
            // Video Input Creator
            
            let videoOutputSettings: Dictionary<String, Any> = [
                AVVideoCodecKey : AVVideoCodecType.h264,
                AVVideoWidthKey : size.width,
                AVVideoHeightKey : size.height
            ];
            
            self.videoInput  = AVAssetWriterInput (mediaType: AVMediaType.video, outputSettings: videoOutputSettings)
            self.videoInput!.expectsMediaDataInRealTime = true
            self.assetWriter!.add(self.videoInput!)
            
            // Create Pixel buffer Adaptor
            
            let sourceBufferAttributes:[String : Any] = [
                (kCVPixelBufferPixelFormatTypeKey as String): Int(kCVPixelFormatType_32ARGB),
                (kCVPixelBufferWidthKey as String): Float(size.width),
                (kCVPixelBufferHeightKey as String): Float(size.height)] as [String : Any]
            
            self.pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: self.videoInput!, sourcePixelBufferAttributes: sourceBufferAttributes);
    
            self.assetWriter?.startWriting();
            self.assetWriter?.startSession(atSourceTime: CMTime.zero);
            completionHandler(nil);
        }
        catch {
            print("Failed to create assetWritter with error : \(error)");
            completionHandler(error);
        }
    }